Case Studies Project Archives
Archive No. 1
Problem. The degradation of iron and steel based structures through corrosion can be a costly problem for building owners to deal with and overcome. Rust results from the interaction between iron or steel and oxygen in the presence of water or airborne moisture. For owners of buildings situated along Sydney's coastal fringes, like the owners of this residential apartment block in Fairlight, one of the most common problem scenarios involving corrosion involves the corrosion of cavity wall ties in the bed joints of the outer brickwork leaf.
Solution. The DryFix remedial wall tie system was used as a cost-effective solution to the problem of corroded wall ties in this building. Undersize 5mm diameter pilot holes were drilled using light-weight rotary percussion drills. DryFix ties (8mm dia.) were then driven into place using a Helifix power driver attachment.
Problem. Contractors were called in to repair and repoint brickwork at this residential apartment block in Bondi Junction, Sydney. After opening up some of the brickwork panels for inspection and in preparation for the commencement of repairs it became apparent that something would also need to be done to address the poor condition of the original wall ties.
Solution. The DryFix remedial wall tie system was again chosen as the simplest and most cost effective solution to the problem. Two thousand DryFix ties were driven into small 5-6mm diameter pilot holes. A suitably coloured mortar was then used to patch over the small holes left in the facade, leaving a well-concealed, solid, mechanical solution.
Problem. Gosford hospital is currently the subject of a major redevelopment project. Large sections of the old hospital have been demolished to make way for the construction of several new facilities and buildings. A number of other sections are being refurbished. As part of the refurbishment plans, project managers decided that it was necessary to retie the cavity walls of this building with stainless steel DryFix (8mm dia.) wall ties. The decision was prompted by the discovery of corroded ties among the existing galvanised wall tie system.
Solution. The DryFix ties needed to be installed quickly in order to minimise the level of disruption to patients and staff. Accordingly, rather than disrupt pedestrian and vehicular traffic contractors worked from ropes to install several thousand DryFix ties into several areas of the building. In other areas, the contractors were able to work quickly from scaffolding and mechanical scissor lifts.
Problem and Solution. Behind the scaffold and cloth sits an historic building that is set to one day house an art gallery. Located in Chippendale, Sydney, this building is no stranger to renovation. Its structure suggests that it has grown outwards and upwards over time.
Originally only a single storey building comprising deep solid walls and high ceilings, it now stands as a large three storey building with even deeper solid walls. At base, these stretch to around 600mm deep. A new chapter in this history is soon to be written with the laying of a new slab now under way at roof level. This new addition is set to make way for a large, outdoor entertainment and function area. However, rather than follow the previous method of adding to the depth of the existing masonry walls to support this new structure, a substantial steel frame has been constructed and the existing walls have been stabilised and strengthened using the Helibeam system.
The deep masonry walls have been stabilised through the installation of 8mm diameter CemTies at regular horizontal and vertical spacings. And to stabilise the masonry above many of arched windows, a combination of CemTies and HeliBars has been used. CemTies have been installed into clearance holes drilled directly into the brick rings that frame each opening. Long lengths of HeliBar have been installed into a number of the mortar beds of the brickwork running across the top of the rings. The CemTies and HeliBars have all been bonded in using high-performance Helibond grout. After repointing and render bagging of the internal walls is completed, little evidence of the presence of either the CemTies or HeliBars will remain.
Problem and Solution. The solid masonry walls of this landmark building in The Rocks, Sydney, were bulging and becoming unstable.
Constructed by convict labour in the early 1800s, the building ranks among the oldest in the country. Today it houses a pub and restaurant, popular among locals and tourists alike.
Given its historical significance and the large number of people who regularly visit and work in it, high on the list of the project engineers concerns were (a) finding a means of repair that could be relied upon to ensure the building's structural integrity and (b) finding a means of structural repair that would not scar the buildings facade. High on the list of concerns for the building's commercial tenants was the request that the necessary remedial work be carried out in a timely and non-disruptive manner.
The Helifix Crack Stitching system was specified to be used to help stabilise one corner of the building. To this end, slots were cut into the mortar joints of the affected area of the wall at a regular vertical spacing. HeliBars (6mm dia.) were then bonded into the slots using HeliBond grout to provide a concealed repair solution. CemTies (10mm dia.) were installed at regular horizontal and vertical intervals into clearance holes that had been drilled directly into the masonry to a depth of around 500mm to help stabilise the deep and bulging eastern wall. High-performance, non-shrink HeliBond grout was again used to bond the CemTies into position.
The work was carried out by experienced contractors who worked outside regular business hours to ensure minimal disruption to the building's occupants.
Cracked and separated walls, Goulburn, NSW
HeliNews: May 2008 | Top
Problem. The drought of recent years contributed to the worsening condition of a number of cracked and separating walls in this grand building in Goulburn, NSW.
Solution. After several years of planning and design, CemTies and the Helibeam System were used to reconnect separated walls and repair cracked arches. The CemTie system was utilised to reconnect many of the separated walls. Clearance holes were drilled through the external wall and deep into the separated internal wall. Long series stainless steel CemTies were then installed into the masonry along with high strength HeliBond grout to provide a strong, fully bonded repair solution. Finally, HeliBars were grouted into the masonry above the cracked masonry arches to restore structural integrity. The work was carried out largely by the building owners themselves, with minimal disruption to the buildings regular operational schedule.
Problem. Manly Council, on Sydney's northern beaches, recently requested owners of buildings with cantilevered awnings extending over public footpaths to provide structural certification demonstrating the integrity and safety of these structures. The request follows a number of incidents involving the collapse and near collapse of awnings in the area. An inspection of one property revealed corroded wall ties and unstable masonry in the parapet wall situated above the awning and return wall running down the northern side of the building.
Solution. Following assessment, the project engineers specified a combination of Helifix repair details to be included as part of an overall repair strategy for this property. The DryFix remedial wall tie system was specified to be used to retie the parapet and return walls while the Helibeam system of bed-joint reinforcement was specified to be used to reinstate strength into the unstable parapet wall. The Helifix repair details were completed within two days and without disruption to the buildings appearance.
